1. Technical Field
The present invention relates to a nitride semiconductor epitaxial substrate having a buffer layer of a group III nitride semiconductor containing Al and a nitride semiconductor device using the same.
2. Description of the Related Art
A technique of reducing dislocation of a group III nitride semiconductor layer is known, wherein a low temperature buffer layer such as AlN and GaN or a high temperature buffer layer such as AlN and AlGaN is provided between a heterogeneous substrate and the group III nitride semiconductor substrate, in a case that a nitride semiconductor epitaxial substrate with the group III nitride semiconductor layer such as GaN, etc., grown thereon, is fabricated on the heterogeneous substrate such as a sapphire substrate and a SiC substrate.
As a proposal regarding the high temperature buffer layer, patent document 1 describes a technique of reducing the dislocation in the group III nitride film formed on the AlN buffer layer by forming unevenness on a surface of the AlN buffer layer (base film).
Patent document 1:
    Japanese Patent Laid Open Publication No. 2002-222771